Down-draft water washed paint spray room



May 22, 1962 1. N. GRESHAM 3,035,507

DOWN-DRAFT WATER wAsHED PAINT SPRAY RooM Filed July 5, 1960 5Sheets-Sheet 1 Y /NVE/vrop /z/G. JOSEPH N. GRESHAM TURNEVS May 22, 1962J. N. GRESHAM 3,035,507

DOWN-DRAFT WATER WASHED PAINT SPRAY ROOM Filed July 5, 1960 5Sheets-Sheet 2 :E 4` rg 111/111111 1111111114;

IIIIIIIIIIIIIII I 5 A' j /NVEA/rof? e 60 6E 90' JOSEPH N.GRESHAM May 22,1962 J. N. GRESHAM 3,035,507

DOWN-DRAFT WATER WASHED PAINT SPRAY ROOM Filed July 5, 1960 3Sheets-Sheet 3 L/Z f,

. /NVENro/i JOSEPH N. GRESHAM Wf/ig United States Patent 3,035,507DWN-DRAFT WATER WASHED PADJT SPRAY ROOM Joseph N. Gresham, 20045Mendelsohn Lane, Saratoga, Calif. Filed July 5, 1960, Ser. No. 40,706 6Ciaims. (Cl. 98-115) The present invention relates to paint spray rooms,and pertains more particularly to a down-draft, waterwashed spray roomand associated mechanism.

In the past, some spray lrooms have been devised wherein a downward ilowof air was provided to urge the paint spray laden air of such roomdownwardly toward the door. Also, prior mechanisms have been devisedusing a water spray to remove air borne paint spray particles from airof the spray room before discharging such air to the atmosphere. Suchprior developments have not, however, fuly solved the problems involved,since they have either been too cumbersome, too expensive, or notentirely satisfactory in their air handling and spray removingcharacteristics.

The present invention provides an improved, downdraft room for paintspraying, water spray means being provided for removal of air bornepaint spray particles from the air as it leaves the room, air evacuatingmeans being provided to maintain an air flow downwardly through the roomand through the spray from the water spray means.

The invention also provides a spray room having air inlet means at thetop `of the room, and a trench extending lengthwise substantially theentire length of the floor thereof, the trench being covered by airadmitting grille means capable of supporting the weight of articles tobe painted thereon, a re-circulating water spray system being providedbeneath the grille means for entraining paint spray particles borne bythe air passing downwardly through the grille means, and means forcausing the water entrained spray particles to be carried to a mainrecovery sump from which water is re-circulated and the paint sprayparticles are removed.

A further object of the invention is to provide a downward air flow,water wash paint spray room into which air is admitted through ceilingducts, is drawn downwardly by air evacuating means into a trench runninglengthwise of the oor of such room, and thence is drawn through lateralduct means the bottom of which are awash with water, the trench having agutter along one side thereof communicating with a small sump adjacentthe gutter, the trench, the gutter, the small sump and the lateral ductsall openly communicating with the main recovery sump.

These, and other objects and advantages of the invention, will beapparent from the following description and the accompanying drawings,wherein:

FG. l is a view partially in section and partially in perspective, thesection being taken along line 1 1 of FG. 2.

EEG. 2 is a sectional view in reduced scale taken along line 2 2 of FIG.l.

FlG. 3 is a sectional view taken along line 3 3 of FIG. 2.

FIG. 4 is an enlarged, sectional view taken along line 4 4 of FIG. 2,intermediate portions thereof being broken away.

FIG. 5 is an enlarged, sectional view taken along line 5 5 of FIG. 2.

FIG. 6 is an enlarged, sectional view taken along line 6 6 of FIG. 2,intermediate portions thereof being broken away.

FIG. 7 is an enlarged, fragmentary sectional view taken along line 7 7of FIG. 6.

Briefly, the illustrated embodiment of the invention comprises a sprayroom 9 having air inlet means 10 in the roof thereof. A trench 11extends longitudinally substantially centrally of the spray room 9, witha deeper gutter portion 12 along one side thereof. An air admittinggrille 13 covers the portion of the trench over the gutter portionthereof, with steel plates 14 covering the remainder of the trench.

A plurality of spray heads 15 are mounted at spaced intervals lengthwisealong the trench 11 beneath the grille 13 and discharge a substantiallycontinuous water spray transversely across beneath the grille to entrainand to remove air-borne spray paint particles from the air. Louvers 16divide the trench medidy longitudinally thereof to equalize and controlthe air ow therethrough. The spray water flows by gravity down the sidewall 17 of the trench 11 into the gutter 12.

Midway of the length of the trench 11, and opening into the gutter 12below the normal water level 13 (FIG. 6) therein, is a small sump 19.This sump 19 communicates by a pipe 2t? with a main recovery sump 21,which preferably is provided exteriorly of the spray room 9. The mainrecovery sump 21 is substantially larger and deeper than the sump 19,and the normal operating water level 18 in the system is such as to lillthe gutter 12 and maintain the bottom 22 of the trench 11 awash with aninch or so of water.

A pair of lateral ducts 23 and 24, the bottoms 25 of which arehorizontal and on the same level as the trench bottom 22, communicatethe trench 11 with a pair of air evacuating stacks 27 and 2S. Each ofthe latter is provided with suitable air ow inducing means such as fans29 and 30. The lateral ducts 23 and 24 also communicate at their outerends with the main recovery sump 2l.

A cylindrical screen 31 (FIGS. 5 and 6) surrounds an inlet pipe 36leading to a water circulating pump 32, which forces water from the mainsump 2l at suitable spraying pressure to the spray nozzles 15.

The pump 32 preferably is provided with a usual back pressure valve (notshown) of a conventional type to keep the pump from losing its primeduring periods of inaction.

A water supply line 33 is provided for adding water to the system asneeded, and a lateral drain pipe 34 is provided for discharging thewater from the system when required.

Referring to the drawings in greater detail, the spray room 9 of theillustrated embodiment A of the invention is a separate building, withroof 35, side walls 37 and 38, end walls 39 and 4G, and oor 41. The airinlet means 1i) in the roof comprises three separate towers 10a, 10b and10c, each with louvered openings 42 in its sides.

Doors 43 and 44 are provided one in each end of the spray room 9 of asuitable size for the admission and removal of articles to be painted insaid room. These doors preferably have a marginal sealing fit with thewalls in which they are mounted in order to 'insure that most of theinlet air enters through the roof air inlet means 10.

The trench 11 extends centrally throughout substantially the entirelength of the spray room 9. rIihe trench bottom 22 is substantiallyhorizontal, and the gutter 12 along one side of the trench extendsseveral inches below the trench bottom 22.

The steel grilles 13 are of a type having a large open area, so as toadmit a free flow of air therethrough. 'Phe grilles 13 are mounted alongthe gutter side of the trench 11, as best shown in FIG. 6. These grillesare made of a size to permit easy handling. One side of each grille issupported on an angle shelf member 45 secured to the trench wall 17,while lthe other sides of the grilles are supported on a structuralsteel girder 47 provided lengthwfise along the trench 11 and braced atrequired intervals by upright posts 4S to support the other side of thegrilles, and also one edge of each of the steel plates 14. The louvers16 are mounted to extend lengthwise of the trench between the posts 48,to which they are rigidly attached. The other side of each of the plates14 from that supported by the central girder 47 lis supported on anangle shelf member 49 secured to the other side of the trench 11 fromthe angle shelf member 45.

rlhe spray heads are mounted on a pipe 5t) which extends lengthwisealong the trench 11 beneath the opposite sides of the grilles 13 fromthe trench side wall 17.

The spray heads 15 are mounted with their axes inclined downwardly, asbest shown in FIG. 6, and directed transversely across the under side ofthe grilles 13 toward the trench side wall 17. The spray heads arepositioned at suiciently close intervals so that a ysubstantiallycontinuous spray of water is discharged from them across beneath thegrilles. The angulanly downwardly directed spray tends to induce an airiiow downwardly through the grilles `13 and thus assists the aircirculating fans 29 and 30 in the stacks in creating a downward flow ofair through the spray room and into the trench.

The small sump 19 beside the trench 11 comprises a rectangular housing51 with a cylindrical liner 52 mounted in axially upright positiontherein. The lower edge of the cylindrical inset 52 is `sealed to thehousing floor 53'. Aligned openings 54 and 55 are provided both in thetrench wall 17 and in the cylindrical liner 52, and the space betweenthe trench wall and the liner is sealed around these aligned openingswith suitable material, such as concrete 57 (FIG. 7). The alignedopenings 54 and 55 are below the normal operating Water level 18 in thesystem, as best shown in FIG. 6, and are also above the bottom of the`gutter 12 and of the small sump 19. This arrangement admits water fromthe gutter 12 into the small sump 19 through the openings 54 and 55, butexcludes scum (not shown) which may be floating on top of such water,and also sludge (not shown) which may collect along the bottom of thegutter 12. From the small sump 19 the return pipe 20 communicates withthe main recovery sump 21.

The main recovery sump 211 is of substantial capacity, so as to allowplenty of time for the heavier entrained particles carried by the waterflowing therein to settle out, and for lighter particles to oat to thesurface. Since the trench 11, gutter 12, and lateral ducts 23 and 24 allcommunicate freely with each other and with the main sump 21 the commonwater level 18 (FIG. 6) tends to be maintained throughout the system.However, since, duning operation of the spray lheads, water isconstantly being withdrawn from the main sump 21 by the pump 32 thisaction tends to lower the water level in the main sump 21 and thus toinduce a gravity ilow of water from these other parts of the systemtoward the main sump.

The lateral ducts 23 and 24 preferably are of substantially the samecross sectional area as the stacks 27 and 28 with which theyrespectively communicate. These lateral ducts preferably are locatedabout one-third of the length of the trench 11 from each end of thelatter. The bottoms of these laterals are horizontal, and are on thesame level with the bottom 22 of the trench '11. Therefore, the bottomsof the lateral ducts will be awash with water like the bottom of themain trench 11 at the normal operating level 18 of the system.

F[ihe outer end of each of the lateral ducts 23 and 24 is in full opencommunication with its respective stack 27 and 2S, and the air inductionmeans in these stacks, such as, for example, the motor driven axial owfans 29 and 30 have a suilicient operating capacity to maintain arequired air llow through these laterale and stacks to produce adownward flow of air in the spray room 9 suicient to draw the air ofsaid room with its air borne paint spray particles downwardly throughthe grilles 13 into the trench 11.

The rear end of the lateral duct 23 communicates through an opening 59(FIG. 5) with the main recovery sump 21, while the rear end of the otherlateral duct 24 communicates with this main sump through the return pipe6G.

A pump mounting shelf 61 is provided on a wall 62 (FIG. 5) of the mainsump, and the water pump 32 is mounted on this shelf. The pump 32 =hasdriven connection with an electnic motor 63 mounted exteriorly of themain 'sump 21. 'The inlet pipe 36 communicates the inlet side of thepump 32 with the main sump 21 well below the normal operating waterlevel 18 in the latter. This inlet pipe is surrounded by the cylindricalscreen 31, which is of sufficiently tine mesh to exclude from the inletpipe 36 water borne paint spray particles carried into the main sumpfrom the other parts of the system.

1rom the outlet side of the pump V32 an outlet pipe 65 is connectedthrough a T-tting 67 to laterally extending pipes 68 and 69, and thence,through pipe lines 70 and 71 to the spray head supporting pipe 50.Valves 73 and 74 provided in the laterally extending pipes 68 and 69control the tlow of water from the pump 32 to the spray heads.

A side outlet T-tting 75 is provided in the main outlet pipe 65 from thepump 32 to the T-litting 67, and the water inlet pipe 33 from a suitablesupply of fresh water such as, for example, a city water supply main(not shown) is connected into this T-iitting. The flow of water throughthe water supply pipe 33 is controlled by a conventional valve 77mounted in said pipe. The drain pipe 34, for draining the system whenrequired, is connected into the side outlet 78 of the T-iitting 75, andthe flow of water through this drain pipe is controlled by aconventional valve 79 mounted therein. The drain pipe 34, as best shownin FIG. l, extends laterally outwardly beyond the main sump 21 for thedis charge of drain water therefrom into any suitable waste waterreceiving equipment that may be provided, such as, for example, aconventional tank truck (not shown).

The operation of the illustrated form A of the invention is as follows:For placing the system in condition for operation, the drain valve 79 isclosed and the pump 32 is at rest. Fresh water is admitted into thesystem by opening the valve 77 communicating with the water supply.While thus lilling the system, the valves 73 and 74 to the spray headsare open.

Water ows into the system through the pipe 65, the lateral pipes 68 and69 and the pipe lines 76 and 71 to the spray heads 15, and is allowed torun until a desired operating water level is attained. When asatisfactory water level in the system has been attained, such as, forexample, that indicated at 18 in FlG. 6, the flow of supply water isshut otl` by closing the water supply valve 77.

With the valves 73 and 74 to the spray heads fully open, the fans 29 and3i) are energized, as is also the water pump motor 63, which places thesystem in operation and ready for use of the spray room 9 for itsintended purpose. The combined downward inclination of the sprays fromthe spray heads 15, plus the suction of the air fans 29 and 30 in thestacks 27 and 28, create an air flow downwardly through the grilles 13into the trench 11, thereby creating a resultant reduction of airpressure within the spray room 9. The latter is well sealed except forthe air inlet means 10 in the roof to insure an adequate downward ilowof air from the air inlet means 10 downwardly through the spray room.

As the paint spray laden air passes through the curtain of water sprayfrom the spray heads 15, said water spray entrains most of the air bornepaint spray particles and carries the latter downwardly as the waterfrom the spray nozzles flows down the trench wall 17 and into the gutter12. From the gutter some of the water flows through the aligned openings54 and 55 into the small sump 19 alongside the trench 11 and thencethrough the return pipe 26 into the main recovery sump 21.

A surface ow of water also is induced by air friction of the air owinglengthwise along the trench 11 toward the lateral ducts 23 and 24, andthen along these lateral ducts toward their respective stacks. Thissurface flow urges any scum (not shown) which may be on the surface ofthe water in the trench and laterals toward the main recovery sump 21.The upper edge of the opening 59 (FIG. 5) from the lateral duct 23 intothe main recovery sump 21 is preferably at or just slightly below thenormal operating water level at this point so that a large part ofthis-iloating scum will be drawn into the main recovery sump withoutsubstantial bleeding of air into the stack through this opening.

Scum, sludge, and suspended solid particles in the main recovery sump 21are prevented from entering the inlet pipe 36 to the pump 32 by thecylindrical screen 31, which is of suiciently ne mesh as to be effectivefor this purpose, such as, for example, the approximate size of thespray nozzle oriiices.

The lower end of the water inlet pipe 64 is well below the normaloperating water level in the system, but is also well above the bottomof the main recovery sump 21, so that the water entering this inlet pipewill tend to draw in a minimum amount of any scum and sludge particleswhich might pass through the screen 31. Scum and sludge may be removedfrom the main recovery sump 21 beyond the screen 31 by suitableskimmers, dredges, or other means of any suitable type, eithermechanical or manual. Since such means form no part of the presentinvention they will not be illustrated or described herein.

Tne invention provides a clean, spray free paint room, with no damagingconcentrated air currents. lt is simple to construct, and easy andeconomical to operate.

`While I have illustrated and described a preferred embodiment of thepresent invention, it will be understood, however, that various changesand modifications may be made in the details thereof without departingfrom the scope of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire toprotect by Letters Patent is defined in the following claims.

I claim:

l. In combination with a paint spraying room sealed on its side wallsand ceiling, air inlet means opening into the top of said room, a trenchextending lengthwise in the oor of said room, an air admitting grille inthe floor of said room over substantially the entire length of saidtrench, a gutter extending lengthwise along one side of said trench,water spray means directed transversely of said trench beneath saidgrille, a small sump at one side of and substantially midway of thelength of the trench and communicating with the gutter below a selectedwater level therein, -a main recovery sump laterally beyond said room,means communicating the small sump with the main recovery sump, a pairof lateral ducts of substantial cross sectional area extending from aside of the trench and beneath the floor of said room and opening to theatmosphere adjacent the main recovery sump, the bottoms of said lateralducts being of substantial area and at a level to be awash duringoperation of the spraying room, means communicating the outer end ofeach lateral duct with the main recovery sump, means for withdrawingwater from the sump and supplying such water to the spray means atsufficient pressure to discharge a substantially continuous spray ofwater from the spray means transversely beneath said grille, means forsupplying water to a selected depth in said trenchv and sumps, aircirculating means for drawing air through the lateral ducts anddischarging it through the laterally outer ends thereof to draw airinwardly through said air inlet means, downwardly through the room andthrough the grille into the trench.

2. In combination with a paint spraying room sealed on its side wallsand ceiling, air inlet means opening into the top of said room, a trenchextending lengthwise in the door of said room, water spray meansdirected transversely across the upper portion of said trench, a firstsump at one side of and substantially midway of the length of the trenchand communicating with the trench below a selected water level therein,a main recovery sump laterally beyond said room, a duct communicatingthe lirst sump with the main recovery sump, a pair of lateral air ductsof substantial cross sectional area extending from a side of the trenchand beneath the floor of said room and opening to the atmosphereadjacent the main recovery sump, the bottoms of said lateral ducts beingon substantially the same level as the bottom of the trench, meanscommunicating the outer end of each lateral duct with the main recoverysump, means for withdrawing water from the main recovery sump andsupplying such water to the spray means at suicient pressure todischarge a substantially continuous spray of Water from the spray meanstransversely of said trench, means for supplying water to a selecteddepth in said trench and sumps sufficient to cover the bottoms of thetrench and of the lateral ducts, air circulating means for drawing airthrough the lateral ducts and discharging it through the laterally outerends thereof to draw air inwardly through said air inlet means,downwardly through the room and into the trench, and thence along thetrench and lateral ducts toward the outer ends of said lateral ducts.

3. In combination with a paint spraying room sealed on its side wallsand ceiling, air inlet means opening into the top of said room, a trenchextending lengthwise in the iioor of said room, an air admitting grillecovering a portion of said trench, a gutter extending lengthwise alongone side of said trench, water spray means directed transversely of, andthroughout substantially the entire length of, said trench beneath saidgrille, a small sump at one side of and substantially midway of thelength of the trench and communicating with the gutter only below aselected water level therein, a main recovery sump laterally beyond saidroom, means communicating the small sump with the main recovery sump, alateral air duct of substantial cross sectional area extending from aside of the trench and beneath the floor of said room and opening to theatmosphere adjacent the main recovery sump, a stack at the outer end ofsaid duct and in open communication therewith, means for supplying waterto a selected level in said trench, said lateral ducts and said sumps,means communicating the outer end of each lateral duct below theselected water level therein with the main recovery sump, power drivenpump means for withdrawing water from the sump and supplying such waterto the spray means at suliicient pressure to dis charge a substantiallycontinuous spray of water from the spray means transversely of saidtrench beneath said grille, air circulating means in said stack fordrawing air from the outer ends of the lateral ducts, thereby to reducethe air pressure in the room and induce a ow of air inwardly throughsaid air inlet means, and downwardly through the room.

4. In combination with a paint spraying room sealed on its side wallsand ceiling, air inlet means opening into the top of said room, a trenchextending lengthwise in the oor of said room, an air admitting grillecovering said trench, a gutter substantially deeper than the trench andextending lengthwise along one side of said trench, water spray meansdirected transversely of said trench beneath said grille, a small sumpat one side of and substantially midway of the length of the trench andcommunicating with the gutter only below a selected water level therein,a main recovery sump laterally beyond said room, means communicating thesmall sump with the main recovery sump, a pair of lateral air ducts ofsubstantial cross sectional area extending from a side of the trench andbeneath the floor of said room and opening to the atmosphere adjacentthe main recovery sump, the bottoms of said lateral ducts being at alevel to remain awash during operation, means communicating the outerend of each lateral duct with the main recovery sump, a pump having itsinlet side communicating with the sump, pipe means communicating theoutlet side of the pump with the spray means to discharge asubstantially continuous spray of water from the spray meanstransversely beneath said grille, means for supplying water to aselected depth in said trench, lateral ducts, and sumps, air circulatingmeans for drawing air through the lateral ducts and discharging itthrough the laterally outer ends thereof to draw air inwardly throughsaid air inlet means, downwardly through the room and through the grilleinto the trench.

5. An arrangement according to claim 4 wherein the grille covers onlyone half the width of the trench on the side overlying said gutter, theremaining half of the trench being covered by substantially air tightcovering means.

6. An arrangement according to claim 5 wherein a plurality of louversare mounted in vertically spaced, inclined position in the form of adivider longitudinally of the trench below the juncture of the grilleand the steel plates to divert air drawn downwardly through the grilleby the air circulating means.

References Cited in the flelof this patent UNITED STATES PATENTS

